C Extensions: calling across extensions

[Martin v. Loewis]

Maxwell Sayles <sayles at cpsc.ucalgary.ca> writes:

> do i need to do special declarations for importing and exporting
> functions across shared objects for python extension modules?  do i need
> to compile with a -l option? 

In general, you can't share symbols across extension modules. You have
the following alternatives:

1. use sys.setdlopenflags (in Python 2.2) to set the flags to RTLD_GLOBAL.
   Notice that this may cause other problems.

2. Create a shared library that contains the code shared across the
   extension modules, and link both extension modules with the shared code.

3. Use the C API to call the code in A from B, just as if you would
   call the code in A from any Python module.

4. Use the CObject to share a C-level API between A and B; see
   cStringIO.c for an example (cStringIO_CAPI).

HTH,
Martin